For producing hot drinks, such as for example coffee, tea, vegetable-based infusions and the like, single-dose packagings, in the form of so-called capsules, pods, cartridges or the like are often used. Here after the term “capsule” will be used to broadly designate such a single-dose packaging. It shall be understood that, unless specifically indicated, said term is to be understood as encompassing any kind of single-dose packaging suitable for preparing beverages or other edible products by extraction using hot and possibly pressurized water. A single dose packaging can include sufficient ingredients to prepare more than just one portion of beverage, e.g. two portions.
Capsules usually contain the ingredients for producing the drink. Hot water is made to flow through the capsule at an adequate pressure to extract the flavours from the ingredients contained in the capsule. There are several types of devices for handling the capsules and for the infusion, that is phase of extracting the flavours from the capsules through water passage.
Some coffee machines are designed for use of loose coffee powder or other loose products. In these machines a dosed quantity of loose product is charged in a brewing chamber. The chamber is closed in a water-tight manner and hot pressurized water is fed from a water heater through the product charged in the brewing chamber, to extract flavours from the ingredients.
U.S. Pat. No. 6,129,006 and EP-A-0931491 disclose a brewing unit specifically intended for brewing coffee from bulk coffee powder. This known brewing unit includes a brewing chamber and a water heater. The water heater is arranged near to the brewing chamber.
Arranging the water heater near the brewing chamber has the advantage of reducing heat dissipation from the heated water along the path from the water heater to the brewing chamber.
One problem of these brewing units, being of the type using pre-packaged single-dose capsules, or loose ingredients, is connected with the need of providing a structure surrounding the brewing chamber which is capable of resisting high mechanical stresses generated by the pressurized water fed through the brewing chamber. For the preparation of espresso coffee, for example, water pressurized up to 8-15 bar flows through the brewing chamber. The force exerted by the water against the portions of the brewing chamber must be supported by a suitably designed frame on which the brewing chamber is mounted. This requires cumbersome structures.